Pastor at the centre of Washington-Ankara dispute is hosted at White House after his release from Turkey.

US President Donald Trump has welcomed freed US pastor Andrew Brunson at the White House, hours after he arrived in Washington back home from Turkey following two years in detention.

"You are very special to us," he told Brunson at the Oval Office meeting on Saturday.

"We've been negotiating long and hard," Trump said, adding that the US paid no ransom to secure Brunson's release.

Trump thanked Turkey's President Recep Tayyip Erdogan for "making this possible" and said the preacher's return to the US marks a "tremendous step" forward in relations with Ankara.

The evangelical pastor was convicted of terror-related charges and sentenced to three years, one month and 15 days in jail on Friday. But he was immediately freed, taking into account the time already served and good conduct during the trial.

Brunson, 50, thanked Trump, saying "you really fought for us", and asked God for "supernatural wisdom" for the US leader.

Pastor Andrew Brunson, released by Turkey, will be with me in the Oval Office at 2:30 P.M. (this afternoon). It will be wonderful to see and meet him. He is a great Christian who has been through such a tough experience. I would like to thank President @RT_Erdogan for his help!

There was NO DEAL made with Turkey for the release and return of Pastor Andrew Brunson. I don’t make deals for hostages. There was, however, great appreciation on behalf of the United States, which will lead to good, perhaps great, relations between the United States & Turkey!

"This is the day our family has been praying for - I am delighted to be on my way home to the United States," Brunson said in a statement after his release.

'The independence of the judiciary'

Brunson was arrested in 2016 as part of the government crackdown in the wake of a failed 2016 coup attempt. He had been under house arrest since July.

Brunson was accused of links with Kurdish rebels and supporters of Fethullah Gulen, whom Turkey blamed for a failed 2016 coup attempt.

Gulen has denied any involvement.

Brunson, who lived in Turkey for more than 20 years, denied the charges and maintained his innocence.

Friday's court decision ends the friction over his case that caused a crisis in relations between the two NATO allies.

"The United States and Turkey have a number of mutual concerns regarding regional security and stability, and we look forward to working together on these issues," the White House said after the pastor's release.

The US claimed was held unjustly and repeatedly called for his release.

With Washington slapping sanctions on Ankara, the crisis also put pressure on the already-falling Turkish lira in August, sparking an economic crisis.

Following the court ruling, an official for the Turkish presidency said the verdict showed the independence of the judiciary in the country.

"Like the Turkish courts, the Republic of Turkey does not receive instructions from anybody, authority, office or person. We make our own rules and make our own decisions that reflect our will," Fahrettin Altun, the presidency's communications director, said in a statement.

Turkish President Erdogan had insisted that he had no sway over the judiciary and that the courts would decide on Brunson's fate.

While Brunson's release is expected to ease tensions between the US and Turkey, further strains remain.

NASA scientist Serkan Golge, a dual US-Turkish national, was jailed for seven and a half years in February on terror charges, a term reduced to five years last month.

Two Turkish employees of US diplomatic missions remain in jail. One of them, former Adana consulate staffer Hamza Ulucay, was on Friday denied release in a separate court hearing.

Secretary of State Mike Pompeo urged Turkey to free "quickly" other Americans in detention after Brunson was released.